The prosecutor general who rose to prominence by standing firm against pressure from the Moon Jae-in administration, shook political minds as he resigned Thursday over moves to deprive the prosecution of its investigative rights, a month ahead of the local by-elections.

Yoon Seok-youl had adhered to the customary reticence of a chief prosecutor, limiting his public speech to parliamentary sessions, until he took his first media interview this week, four months before his two-year term was to expire in July.

His resignation also came on the same day the main opposition People Power Party announced Oh Se-hoon as their candidate for Seoul mayor, raising speculation over how all this would pan out toward the presidential election a year from now.

PPP’s interim leader Kim Chong-in said he would meet with Yoon if he wants to.

PPP floor leader Joo Ho-young said his party would join forces with Yoon if necessary.

Having stood up against former Justice Minister Choo Mi-ae, who was legally his boss, and against the prosecutorial reformists, Yoon said Thursday, “The constitutional spirit and the rule of law that have supported this country are crumbling. The damage will only go to the Korean people.”

He said he would do his best to protect free democracy and the Korean people regardless of where he stands, leaving open the question of whether he will run for government office.

Many observers in the opposition think Yoon will watch how the opposition sorts out differences to field a single candidate for Seoul mayor against the ruling party in the by-election next month, and wait till his value peaks after they start gearing up for the presidential race.

Some say Yoon is likely to rule out joining the PPP, and rally centrists to form his own political support base.

The ruling Democratic Party has slammed Yoon, accusing him of acting politically.

DP leader Lee Nak-yon said Yoon’s resignation “out of the blue” was absurd for a public official.

“The impact he had on the prosecution will be judged in time. It is ironical that now, recovering the prosecution’s political neutrality has also become a pending task,” Lee said during a party meeting.

What triggered Yoon’s resignation was the ruling party’s plan to launch a separate agency for “serious crimes” such as abuse of power and corruption, which would leave the prosecution with only the rights to request court warrants and indict suspects.

Yoon’s resignation, which Moon accepted an hour later, puts the ruling bloc’s serious crime agency plan in a predicament.

If the Democratic Party withdraws the scheme, it would be taken by opponents as an admission that the purpose of the latest prosecutorial reform efforts was to remove Yoon.

If they push ahead with the plan, it could backfire by becoming a political rallying point for Moon’s opponents.

On Wednesday, a day ahead of his resignation, Yoon visited the Daegu High Prosecutors’ Office and the Daegu District Prosecutors’ Office, and voiced his opposition to the “serious crimes” agency scheme.

He and others who oppose the Moon administration’s reforms have insisted that creating the new crime agency would allow those currently in power to avoid anti-corruption probes after they lose power.

Insisting that he cannot accept depriving the prosecution of investigative rights, as it would degrade its capability to fight corruption, Yoon suggested dividing the prosecution instead to create agencies for anti-corruption, financial crimes and narcotics that would run outside the command of the prosecutor general.

After Yoon took helm in 2019, the prosecution has investigated former Justice Minister Cho Kuk and his family over document forgery and illegal investments; suspicions that presidential aides pulled strings to make President Moon’s friend win a mayoral election; and allegations that the government fabricated data in its economic feasibility assessment of the Wolsong-1 nuclear reactor.

His grim defiance, coinciding with the teetering approval ratings of Moon mostly over property policy failures, pushed up his popularity in opinion polls as the most preferred potential presidential candidate.

Jung Jin-seok, chief of the People Power Party’s committee that decides which candidates to field under the party’s ticket, said Yoon endured “humiliation and persecution” under Cho and Choo.

By Kim So-hyun (sophie@heraldcorp.com)